Gear sense

Detail of bicycle seatstay with Di2 Bluetooth attachment

The past weekend would have been fine for riding. Cold, but with clear skies. A threat of wind on Saturday that never really materialized, after a ferociously windy Friday. Unfortunately I had other commitments on Sunday.

So instead of riding Saturday, I decided to upgrade my recent upgrade — so recent I’ve only had one ride on the bike since adding the electronic shifting (and hydraulic brakes). Shimano’s Bluetooth unit allows the Di2 shifting system to communicate with the Garmin GPS device, allowing me to see things like current gear selection and battery level.

Adding the sensor to the bike just took a couple of minutes. I already had the required additional wire from the first go, when all the wires I’d bought were too short. Then connecting to the Garmin was a doddle. (I took the last screenshot just now, stepping out on the balcony to wake up the Di2 system, which explains the night mode.)

The number of teeth shown front and rear (“Front Gears” and “Rear Gears” in the middle shot, and “Gear Combo” in the last shot) isn’t correct, but everything else should be. (I’ve just now input the correct values after noticing this, but I can’t be bothered at the moment to create new screenshots.)

What advantages does that bring ie having that information on your Garmin

Fearless Leader Joe

It’s just another toy, really

It would be nice to have the current gear selection pop up on the Garmin whenever I’m switching gears (but not otherwise). As Fearless Leader Joe noted, I usually have a good idea about where I am on the gears, and it’s not critical to know the exact gear. The exception is when I’m braking to stop: I want to start up in the large chainring on front and the No. 2 cog on the back — the combo shown in the screenshot above (except it’s actually 44-30). But it’s easy enough for me to shift all the way to the largest cog and then up one.

The real benefit is the read-out of the battery level. Without the Bluetooth add-on giving me a precise percentage, I just have to interpret the LED on the front junction box: 0%, 25%, 50%, 100%. And I have to press the button each time to read the LEDs. The Garmin read-out is a huge improvement on that. (Of course, I still have to remember to check the charge before it’s time to get on the bike and ride — as FLJ’s brother can attest.)

As a finishing touch, I added a couple of wire guides to the seatstay to keep those expensive Di2 wires out of the gears and spokes. (Took the photo before adding the guides, naturally … )

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